let lis = document.querySelector('.tab_list').querySelectorAll('li');
let items = document.querySelectorAll('.item');
for (let i = 0; i < lis.length; i++) {
    lis[i].setAttribute('data-index',i);
    lis[i].onmouseover = function () {
        for (let k = 0; k < lis.length; k++) lis[k].className = '';
        this.className = 'current';
        for (let k = 0; k < items.length; k++) items[k].style.display = 'none';
        items[this.getAttribute('data-index')].style.display = 'block';
    }
}